1. Field of the Invention
The present invention relates to a coating apparatus for and a coating method of coating a web with a coating solution which is discharged through lips of a die supported by a mounting, and more especially to a coating apparatus for and a coating method of coating a flexible web, such as a plastic film, a paper, a metal foil and the like, with a coating solution, such as a photosensitive emulsion agent, a magnetic liquid, a liquid for providing antireflective properties and antiglare properties, liquid for providing a view angle enlarging effect, a liquid pigment for a color filter, a surface protection liquid, and the like, so as to obtain a high functional multi-layer film.
2. Description Related to the Prior Art
In order to produce a multi-layer film having high functions, a coating apparatus including a die makes a coating of a web with coating solutions so as to form stacked layers from the coating solutions on the web. In recent years, in order to realize required functions, a technique for constructing the stacked layers at high accuracy with small wet film thickness at most 20 μm. In this case, the accuracy of each part in the coating apparatus is made higher such that the accuracy of a clearance between lips of the die and a web may be higher. Therefore, in Japanese Patent Laid-Open Publication No. 5-111672, a mounting and the die are formed from the same materials, and thus the difference of thermal expansion coefficient between the mounting and the die is smaller. Further, in Japanese Patent Laid-Open Publication No. 2000-176343, elements of the die are assembled on the mounting with keeping the temperature of the elements and the mounting at the same value as that for the coating. Furthermore, Japanese Patent Laid-Open Publication No. 2003-112100 describes demerits of assembling elements onto a die whose accuracy is not high. Further in this publication, in order to solve the problems of these demerits, an improvement of a method of fixing the die to the mounting is described.
However, in the above three publications, the consideration for increasing the accuracy of the mounting is not enough. Usually, the mounting is made by welding for easiness of the production. In the welding, however, it is difficult to produce the mounting with the accuracy in μm order. Therefore the increase of the accuracy of the clearance between the lips and the web is prevented. Further, in the above publications, it is not considered to keep the accuracy during the coating, but to increase the accuracy before the coating. Therefore, the accuracy of the clearance between the lips and the web decreases during the coating.